This invention relates to an air filter connecting unit having a connecting flange and a connecting nipple which can be connected to the flange by a snap connection.
Air filter connecting units serve to connect an air filter housing with an air conduit element, e.g., a hose, that conveys the filtered air further. The air conduit element is usually pushed onto a connecting nipple on the air filter housing. Especially when the air conduit element contains predetermined bends or the connecting nipple is designed to be angled, it may be necessary to provide rotatability of the connecting nipple with respect to the connecting flange in order to be able to push the air conduit element into place in a first angular position and then be able to position it in the engine space by rotating the connecting nipple so that it is situated in the area intended for it. Rotatability is also helpful in dissipating any torsional stresses that might arise.
With an air filter connecting unit known from U.S. Pat. No. 5,882,367, a snap connection is provided, allowing the connecting nipple to rotate with respect to the flange after the connecting nipple has been inserted into the receiving recess in the flange. The snap connection comprises an obliquely angled shoulder on the flange which is resiliently deformed due to a thickened area on the connecting nipple and springs back behind the thickened area, so that the connection is established.
The strength of such a snap connection depends on the height and holding angle of the undercut. Since the joining forces depend on the joining angle and also on the undercut, this yields a mutual dependence. In manual assembly, the joining forces are limited, in particular in the case of an unfavorable installation position in a tight engine space, and therefore the holding forces that can be achieved are also limited.